The effect of sub-zero cooling on microstructure and mechanical properties of a low alloyed austempered ductile iron has been investigated. Austempering of samples was performed at 325℃and 400℃after austenitizing at...The effect of sub-zero cooling on microstructure and mechanical properties of a low alloyed austempered ductile iron has been investigated. Austempering of samples was performed at 325℃and 400℃after austenitizing at 875℃and 950℃. The sub-zero treatments were carried out by cooling down the samples to -30℃, -70℃and -196℃. The changes in volume fraction of austenite and mechanical properties were determined after cooling to each temperature. The austenite volume fraction of samples which were austenitized at 875℃and austempered at 325℃remained unchanged, whilst it reduced in samples austenitized at 950℃and 875℃for austempering temperature of 400℃. In these specimens, some austenite transformed to martensite after subzero cooling. Mechanical property measurements showed a slight increase in strength and hardness and decrease in elongation and toughness due to this transformation behavior.展开更多
Plasma electrolytic oxidation(PEO)is a promising surface treatment to generate adherent and thick anti-corrosive coating on light-weight metals(Al,Mg,Ti,etc.)using an eco-friendly alkaline electrolyte.High energy plas...Plasma electrolytic oxidation(PEO)is a promising surface treatment to generate adherent and thick anti-corrosive coating on light-weight metals(Al,Mg,Ti,etc.)using an eco-friendly alkaline electrolyte.High energy plasma,however,inevitably generates porous structures that limit their practical performance.The present study proposes a straight-forward simple method by utilizing sub-zero electrolyte(268 K)to alter the plasma characteristics during formation of the protective coating on AZ31 Mg alloy via PEO with a comparison to the electrolyte at room temperature(298 K).In refrigerated electrolyte,the formation of micro-defects is suppressed relatively at the expense of low coating growth,which is measured to be twice lower than that at 298 K due to the temperature-dependent soft plasma discharges contributing to the development of the present coating.As a consequence,corrosion resistance of the sample processed at 268 K is superior to that of 298K,implying that the effect of coating thickness is less dominant than that of compactness.This phenomenon is interpreted in relation to the ionic movement and oxide solidification controlled by soft plasma discharges arising from the temperature gradient between electrolyte and surface of the substrate during PEO.展开更多
In this work, the influence of sub-zero Celsius treatment and tempering on the mechanical and thermal stability of retained austenite in beating steel were assessed by tensile test and DSC. Compared with traditional q...In this work, the influence of sub-zero Celsius treatment and tempering on the mechanical and thermal stability of retained austenite in beating steel were assessed by tensile test and DSC. Compared with traditional quenched and tempered treatment, sub-zero Celsius treatment obviously decreases the volume fraction of retained austenite. Moreover, the mechanical stability of retained austenite was enhanced due to the accumulation of compressive stresses in retained austenite after sub-zero Celsius treatment and tempering. Meanwhile, the morphology of retained austenite changed from film-like to blocky with austenitization temperature increasing, and the mechanical stability of film-like retained austenite is higher than that of blocky one. The DSC results showed that the activation energy of retained austenite decomposition slightly increased through sub-zero Celsius treatment and tempering. This result may probably be ascribed to partitioning of carbon during tempering. However, the temperature at which retained austenite starts to decompose is unchanged.展开更多
This research investigates the comparative efficacy of generating zero divisor graphs (ZDGs) of the ring of integers ℤ<sub>n</sub> modulo n using MAPLE algorithm. Zero divisor graphs, pivotal in the study ...This research investigates the comparative efficacy of generating zero divisor graphs (ZDGs) of the ring of integers ℤ<sub>n</sub> modulo n using MAPLE algorithm. Zero divisor graphs, pivotal in the study of ring theory, depict relationships between elements of a ring that multiply to zero. The paper explores the development and implementation of algorithms in MAPLE for constructing these ZDGs. The comparative study aims to discern the strengths, limitations, and computational efficiency of different MAPLE algorithms for creating zero divisor graphs offering insights for mathematicians, researchers, and computational enthusiasts involved in ring theory and mathematical computations.展开更多
Let G = Γ(S) be a semigroup graph, i.e., a zero-divisor graph of a semigroup S with zero element 0. For any adjacent vertices x, y in G, denote C(x,y) = {z∈V(G) | N (z) = {x,y}}. Assume that in G there exi...Let G = Γ(S) be a semigroup graph, i.e., a zero-divisor graph of a semigroup S with zero element 0. For any adjacent vertices x, y in G, denote C(x,y) = {z∈V(G) | N (z) = {x,y}}. Assume that in G there exist two adjacent vertices x, y, a vertex s∈C(x,y) and a vertex z such that d (s,z) = 3. This paper studies algebraic properties of S with such graphs G = Γ(S), giving some sub-semigroups and ideals of S. It constructs some classes of such semigroup graphs and classifies all semigroup graphs with the property in two cases.展开更多
目的:比较零下非结冰(-0.8℃)UW液、Cel-sior液和HTK液保存生物人工肝用L-02细胞的效果.方法:将制备好的L-02细胞悬液分成以下3组:UW液保存组(UW液组);Celsior液保存组(CS液组);HTK液保存组(HTK液组).各组细胞于-0.8℃低温保存72h后,分...目的:比较零下非结冰(-0.8℃)UW液、Cel-sior液和HTK液保存生物人工肝用L-02细胞的效果.方法:将制备好的L-02细胞悬液分成以下3组:UW液保存组(UW液组);Celsior液保存组(CS液组);HTK液保存组(HTK液组).各组细胞于-0.8℃低温保存72h后,分别使用流式细胞术测定细胞存活率及死亡率,谷丙转氨酶(ALT)及乳酸脱氢酶(LDH)释放,尿素合成功能及白蛋白分泌功能.结果:UW液较Celsior液和HTK液显著提高了零下非结冰保存72h的L-02细胞的存活率(71.10%±4.09%vs65.22%±4.45%,50.48%±5.13%,均P<0.05);降低了细胞死亡率(29.90%±4.09%vs34.78%±4.45%,49.52%±5.13%,均P<0.05);抑制了ALT(6.18U/L±1.36U/L vs8.15U/L±1.14U/L,9.75U/L±2.45U/L,均P<0.05)和LDH(93.82U/L±5.68U/Lvs115.67U/L±8.77U/L,164.92U/L±15.95U/L,均P<0.05)释放;更好地维持了L-02细胞尿素合成功能(1.08mmol/L±0.22mmol/Lvs0.92mmol/L±0.17mmol/L,0.68mmol/L±0.08m m o l/L,均P<0.05)和白蛋白分泌功能(9.33mg/L±1.36mg/L vs7.54mg/L±1.22mmol/L,7.18mg/L±0.93mg/L,均P<0.05).结论:同Celsior液和HTK液相比,使用UW液零下非结冰(-0.8℃)保存肝细胞可以明显提高复温后细胞存活率,降低低温损伤引起的ALT、LDH释放,有效保护肝细胞尿素合成功能和白蛋白分泌功能.展开更多
文摘The effect of sub-zero cooling on microstructure and mechanical properties of a low alloyed austempered ductile iron has been investigated. Austempering of samples was performed at 325℃and 400℃after austenitizing at 875℃and 950℃. The sub-zero treatments were carried out by cooling down the samples to -30℃, -70℃and -196℃. The changes in volume fraction of austenite and mechanical properties were determined after cooling to each temperature. The austenite volume fraction of samples which were austenitized at 875℃and austempered at 325℃remained unchanged, whilst it reduced in samples austenitized at 950℃and 875℃for austempering temperature of 400℃. In these specimens, some austenite transformed to martensite after subzero cooling. Mechanical property measurements showed a slight increase in strength and hardness and decrease in elongation and toughness due to this transformation behavior.
基金the Mid-Level Researcher National Project of the National Research Foundation(NRF)funded by the Ministry of Science and ICT,Republic of Korea(NRF-2020R1A2C2004192)supported partly by the Competency Development Program for Industry Specialist of the Korea Institute for Advancement of Technology(KIAT)funded by the Ministry of Trade,Industry,and Energy,Republic of Korea(P0002019)。
文摘Plasma electrolytic oxidation(PEO)is a promising surface treatment to generate adherent and thick anti-corrosive coating on light-weight metals(Al,Mg,Ti,etc.)using an eco-friendly alkaline electrolyte.High energy plasma,however,inevitably generates porous structures that limit their practical performance.The present study proposes a straight-forward simple method by utilizing sub-zero electrolyte(268 K)to alter the plasma characteristics during formation of the protective coating on AZ31 Mg alloy via PEO with a comparison to the electrolyte at room temperature(298 K).In refrigerated electrolyte,the formation of micro-defects is suppressed relatively at the expense of low coating growth,which is measured to be twice lower than that at 298 K due to the temperature-dependent soft plasma discharges contributing to the development of the present coating.As a consequence,corrosion resistance of the sample processed at 268 K is superior to that of 298K,implying that the effect of coating thickness is less dominant than that of compactness.This phenomenon is interpreted in relation to the ionic movement and oxide solidification controlled by soft plasma discharges arising from the temperature gradient between electrolyte and surface of the substrate during PEO.
基金financially supported by the National Basic Research Program of China (No. 2011CB706604)National Natural Science Foundation of China (No. 51174251 and 51201105)
文摘In this work, the influence of sub-zero Celsius treatment and tempering on the mechanical and thermal stability of retained austenite in beating steel were assessed by tensile test and DSC. Compared with traditional quenched and tempered treatment, sub-zero Celsius treatment obviously decreases the volume fraction of retained austenite. Moreover, the mechanical stability of retained austenite was enhanced due to the accumulation of compressive stresses in retained austenite after sub-zero Celsius treatment and tempering. Meanwhile, the morphology of retained austenite changed from film-like to blocky with austenitization temperature increasing, and the mechanical stability of film-like retained austenite is higher than that of blocky one. The DSC results showed that the activation energy of retained austenite decomposition slightly increased through sub-zero Celsius treatment and tempering. This result may probably be ascribed to partitioning of carbon during tempering. However, the temperature at which retained austenite starts to decompose is unchanged.
文摘This research investigates the comparative efficacy of generating zero divisor graphs (ZDGs) of the ring of integers ℤ<sub>n</sub> modulo n using MAPLE algorithm. Zero divisor graphs, pivotal in the study of ring theory, depict relationships between elements of a ring that multiply to zero. The paper explores the development and implementation of algorithms in MAPLE for constructing these ZDGs. The comparative study aims to discern the strengths, limitations, and computational efficiency of different MAPLE algorithms for creating zero divisor graphs offering insights for mathematicians, researchers, and computational enthusiasts involved in ring theory and mathematical computations.
文摘Let G = Γ(S) be a semigroup graph, i.e., a zero-divisor graph of a semigroup S with zero element 0. For any adjacent vertices x, y in G, denote C(x,y) = {z∈V(G) | N (z) = {x,y}}. Assume that in G there exist two adjacent vertices x, y, a vertex s∈C(x,y) and a vertex z such that d (s,z) = 3. This paper studies algebraic properties of S with such graphs G = Γ(S), giving some sub-semigroups and ideals of S. It constructs some classes of such semigroup graphs and classifies all semigroup graphs with the property in two cases.
文摘目的:比较零下非结冰(-0.8℃)UW液、Cel-sior液和HTK液保存生物人工肝用L-02细胞的效果.方法:将制备好的L-02细胞悬液分成以下3组:UW液保存组(UW液组);Celsior液保存组(CS液组);HTK液保存组(HTK液组).各组细胞于-0.8℃低温保存72h后,分别使用流式细胞术测定细胞存活率及死亡率,谷丙转氨酶(ALT)及乳酸脱氢酶(LDH)释放,尿素合成功能及白蛋白分泌功能.结果:UW液较Celsior液和HTK液显著提高了零下非结冰保存72h的L-02细胞的存活率(71.10%±4.09%vs65.22%±4.45%,50.48%±5.13%,均P<0.05);降低了细胞死亡率(29.90%±4.09%vs34.78%±4.45%,49.52%±5.13%,均P<0.05);抑制了ALT(6.18U/L±1.36U/L vs8.15U/L±1.14U/L,9.75U/L±2.45U/L,均P<0.05)和LDH(93.82U/L±5.68U/Lvs115.67U/L±8.77U/L,164.92U/L±15.95U/L,均P<0.05)释放;更好地维持了L-02细胞尿素合成功能(1.08mmol/L±0.22mmol/Lvs0.92mmol/L±0.17mmol/L,0.68mmol/L±0.08m m o l/L,均P<0.05)和白蛋白分泌功能(9.33mg/L±1.36mg/L vs7.54mg/L±1.22mmol/L,7.18mg/L±0.93mg/L,均P<0.05).结论:同Celsior液和HTK液相比,使用UW液零下非结冰(-0.8℃)保存肝细胞可以明显提高复温后细胞存活率,降低低温损伤引起的ALT、LDH释放,有效保护肝细胞尿素合成功能和白蛋白分泌功能.
